This invention pertains to sensor alignment circuits and methods of operating apparatus having the same, and particularly to sensor alignment circuits wherein an indication is required of the relative positioning of sensing means with respect to sensed indicia borne by articles traveling proximate the sensing means.
Many indicia reading systems, such as bar code reading systems used in the postal environment, for example, require precision positioning of a reading or sensing means. Typically the sensing means is situated proximate a traveling web of documents or a conveyor transporting documents. The documents generally bear a printed indicia which must pass near or under the sensing means. For computer-generated documents, however, the print position of the indicia tend to drift so that after extensive printing the sensing means may no longer be precisely aligned with respect to the indicia.
When misalignment of sensing means and indicia occurs, the position of the sensing means must be readjusted. The precise repositioning of the sensing means is often a tricky maneuver requiring the use of an oscilloscope by a trained technician. As a result, repositioning of sensing means has heretofore involved expensive and time consuming service calls.
Hence, an object of this invention is the provision of a sensor alignment circuit which enables a machine operator to quickly and simply reposition the sensing means with respect to sensed indicia borne by documents traveling proximate the sensing means.
An advantage of this invention is the provision of sensor alignment circuit which provides an indication of sensing means positioning relative to a sensed indicia regardless of any change in the speed of travel of indicia-bearing documents traveling proximate the sensing means.